Diorganocarbonates, typically dimethyl carbonate, may be prepared by the oxidative carbonylation of alcohols in the presence of a catalyst. Typically methanol is reacted with carbon monoxide and oxygen to prepare dimethyl carbonate. The reaction is carried out in the presence of a catalyst; and those skilled in the art constantly seek new catalysts to lower costs, and to improve reaction conditions, yield, rate of production, etc.
There is a substantial body of prior art relating to the production of organic carbonates. Illustrative of these references are the following:
U.S. Pat. No. 3,114,762 to Mador et al discloses as catalysts metal salts including chlorides and bromides of platinum and palladium plus an oxidizing agent such as iron or copper salts having the same anion.
U.S. Pat. No. 3,227,740 to Fenton discloses as catalyst mercuric halides or carboxylates.
Saegusa et al, J. Org Chem., 35, 2976-2978 (1970) discloses the reaction of CO with copper alkoxides including the dimethoxide, the di-allyloxide, the chloride methoxide, and the acetylacetonate methoxide.
Romano et al IEC Prod. Res. Dev. 19, 396-403 (1980) discloses as catalyst cuprous chloride/cupric chloride methoxide.
U.S. Pat. No. 4,218,391 to Romano et al discloses as catalysts salts of metals of Group IB, IIB, and VIII, preferably monovalent copper such as cuprous bromide, chloride, or perchlorate.
U.S. Pat. No. 4,318,862 to Romano et al discloses as catalyst salts of metals of Groups IB, IIB, or VIII, typically a copper salt such as CuCl.
U.S. Pat. No. 3,846,468 to Perrotti et al discloses as catalysts cuprous chloride complexes with an organic ligand such as pyridine, dipyridyl, imidazole, phenanthroline, alkyl or aryl phosphines, dimethyl sulfoxide, dimethyl formamide, quinuclidine, acetonitrile, benzonitrile, malonitrile, succinodinitrile, or adiponitrile.
U.S. Pat. No. 3,980,690 to Cipriani et al discloses as catalyst a complex of copper chloride and poly-4-vinylpyridine.
Rivetti et al, J. Organometallic Chem, 174 (1979) 221-226 discloses as catalysts palladium(II) complexes in the presence of ligands and added bases. Alkyl phosphines are said to inhibit carbonylation almost completely. The presence of tertiary amines enhances the formation of dimethyl carbonate. Low yields (6% or less) of dimethyl carbonate are obtained with Pd(OAc).sub.2 in the presence of ligands such as R.sub.3 P where R is p--C.sub.6 H.sub.4 OCH.sub.3. Yield is increased to 61% in the presence of base such as diisopropylethylamine.
U.S. Pat. No. 3,952,045 to Gaenzler et al discloses as catalysts organic phosphorus compounds such as phosphine oxide, phosphite, phosphate, or phosphonate plus copper halides.
U.S. Pat. No. 4,360,477 to Hallgren et al discloses as catalysts cupric halides inter alia.
Yang et al CA 86, 171868u (1977) discloses as catalysts PdCl.sub.2, CuCl.sub.2, MnCl.sub.2, and LiCl.
Lapidus et al CA 93, 72328j (1980) discloses as catalysts MnCl.sub.2, KMnO.sub.4, CuCl.sub.2, LiCl, and Mn(OAc).sub.3.
Itatani, Japanese patent publication 54-24827 pub 24 Feb. 1979 discloses as catalysts cuprous halides plus as auxiliary catalyst a halide of an alkali metal or an alkaline earth metal.
U.S. Pat. No. 4,370,275 to Stammann et al discloses as catalysts compositions containing copper, chemically bonded oxygen, and halogen and a nitrogen base. A typical catalyst contains CuO or Cu(OCl).sub.2 and n-butylamine inter alia. Preferred combinations include: CuCO.sub.3, Cu(OH).sub.2 ; CuCl.sub.2 and pyridine hydrochloride etc.
U.S. Pat. No. 4,131,521 to Cipris et al discloses an electrochemical process utilizing a non-fluoride halide-containing electrolyte.
U.S. Pat. No. 4,113,762 to Gaenzler et al discloses as catalysts complexes of copper (as CuCl) with VCl.sub.3, CrCl.sub.3, FeCl.sub.3, CoCl.sub.2, AlCl.sub.3 or SiCl.sub.4.
U.S. Pat. No. 4,361,519 to Hallgren discloses as catalysts (i) Bronsted bases such as a quaternary ammonium, phosphonium, or sulfonium compound or an alkoxide or hydroxide of alkali metal or alkaline earth metal or a salt of a strong base and a weak acid or amines etc. plus (ii) a Group VIIIB element Ru, Rh, Pd, Os, Ir, or Pt plus (iii) oxygen plus (IV) a redox catalyst such as a Mn or Co containing catalyst. A typical system includes (i) a pentamethylpiperidine, (ii) PdBr.sub.2 and (iii) pyridine adduct of salicylaldehyde-ethylene diamine Co(II) complex.
European Pat. No. 0,071,286 to Drent discoses as catalysts copper compounds such as halide (in the presence of an amine) plus a sulfone such as dimethyl sulfone or a sulfolane.
It is an object of this invention to provide a method for preparation of dimethyl carbonate. Other objects will be apparent to those skilled in the art.